An infrastructure based wireless local area network (LAN) is defined as one in which there is, within a single logical link layer wireless LAN segment, a designated network node that performs control of membership of that link layer segment, by way of an association function, and may also, but not necessarily, have access to means of communication with other wired or wireless link layer LAN segments. The designated network node is referred to as an access point (AP), which includes an association function for control of membership of the segment and also contains a logical transport to other segments. The logical transport to the other segments is referred to as a distribution system (DS). The DS may be null if there is no other link layer segment.
FIG. 1 is a block diagram illustrating prior art LAN segments. Typically, data packets to be sent from a source node to a destination node are first sent to the AP with which the source node is associated. The AP then determines whether the destination node is also associated with it or with another AP. If the destination node is associated with another AP, then the destination node may only be reached via the DS. For example, referring to FIG. 1, when the source node 115 wants to send data to the destination node 120 (illustrated by the dotted arrow), it first sends the data to the AP 110 using path 155. Because the destination node 120 is also associated with the AP 110, the AP 110 then forwards the data to the destination node 120 using path 156. As another example, when the source node 115 wants to send data to the destination node 125, it first sends the data to the AP 110 using the path 155. Because the destination node 125 is associated with another AP 105, the AP 110 needs to forward the data to the AP 105 using path or DS 160. The AP 105 then forwards the data to the destination node 125 using the path 165. The process of forwarding the data from the source node to the destination node in both examples is inefficient because more network resources are used to transmit the same data more than once before the destination node receives the data.
There are schemes that may be followed to set up and maintain direct links between a source node and a destination node so that data may be sent directly from the source node to the destination node. For example, one of these schemes is described in a document titled “Wireless Address Resolution Protocol” (Document IEEE 802.11-02/016r0) by Duncan Kitchin of Intel Corporation. Another scheme is described in a document titled “Direct Stream Request Protocol (DSRP)” (Document IEEE 802.11-02/421r0) by Menzo Wentink of Intersil Corporation. Using one of these schemes, the data may be transferred directly from a source node to a destination node. For example, referring to FIG. 1, the source node 115 may send data directly to the destination node 120 without having to first send the data to the AP 110.
Even though the proposals mentioned above describe how to set up and maintain the direct links, they fail to provide adequate support for dynamic network topology resulting from devices moving to different locations. For example, these proposals use a time out approach to enable a source node to recognize that a destination node that it has been communicating is no longer positioned in the same location. The proposals, however, does not address how to reroute data to the destination node at its new location.